feat: add positive number validation rule (#82)

Author: ns-vasilev

README.md

@@ -309,6 +309,7 @@ struct RegistrationView: View {
 | `EmailValidationRule` | Validates email format | `EmailValidationRule(error: "Please enter a valid email")` |
 | `CharactersValidationRule` | Validates that a string contains only characters from the allowed CharacterSet | `CharactersValidationRule(characterSet: .letters, error: "Invalid characters")` |
 | `NilValidationRule` | Validates that value is nil | `NilValidationRule(error: "Value must be nil")`
+| `PositiveNumberValidationRule` | Validates that value is positive | `PositiveNumberValidationRule(error: "Value must be positive")`
 
 ## Custom Validators
 

Sources/ValidatorCore/Classes/Rules/PositiveNumberValidationRule.swift

@@ -0,0 +1,35 @@
+//
+// Validator
+// Copyright © 2025 Space Code. All rights reserved.
+//
+
+/// Validates that a number is positive.
+///
+/// # Example:
+/// ```swift
+/// let rule = PositiveNumberValidationRule(error: "Value must be positive")
+/// rule.validate(input: -1) // false
+/// rule.validate(input: 10) // true
+/// ```
+public struct PositiveNumberValidationRule: IValidationRule {
+    // MARK: Types
+
+    public typealias Input = Double
+
+    // MARK: Properties
+
+    /// The validation error.
+    public let error: IValidationError
+
+    // MARK: Initialization
+
+    public init(error: IValidationError) {
+        self.error = error
+    }
+
+    // MARK: IValidationRule
+
+    public func validate(input: Double) -> Bool {
+        input > 0
+    }
+}

Sources/ValidatorCore/Validator.docc/Overview.md

@@ -31,6 +31,8 @@ ValidatorCore contains all core validation rules, utilities, and mechanisms for
 - ``RegexValidationRule``
 - ``SuffixValidationRule``
 - ``URLValidationRule``
+- ``NilValidationRule``
+- ``PositiveNumberValidationRule``
 
 ### Articles
 

Tests/ValidatorCoreTests/UnitTests/Rules/PositiveNumberValidationRuleTests.swift

@@ -0,0 +1,56 @@
+//
+// Validator
+// Copyright © 2025 Space Code. All rights reserved.
+//
+
+import ValidatorCore
+import XCTest
+
+// MARK: - PositiveNumberValidationRuleTests
+
+final class PositiveNumberValidationRuleTests: XCTestCase {
+    // MARK: Properties
+
+    private var sut: PositiveNumberValidationRule!
+
+    // MARK: XCTestCase
+
+    override func setUp() {
+        super.setUp()
+        sut = PositiveNumberValidationRule(error: String.error)
+    }
+
+    override func tearDown() {
+        sut = nil
+        super.tearDown()
+    }
+
+    // MARK: Tests
+
+    func test_thatPositiveNumberValidationRuleSetsProperties() {
+        // then
+        XCTAssertEqual(sut.error.message, .error)
+    }
+
+    func test_thatPositiveNumberValidationRuleValidatesInput_whenInputIsCorrectValue() {
+        // when
+        let result = sut.validate(input: 10)
+
+        // then
+        XCTAssertTrue(result)
+    }
+
+    func test_thatPositiveNumberValidationRuleValidatesInput_whenInputIsIncorrectValue() {
+        // when
+        let result = sut.validate(input: -1)
+
+        // then
+        XCTAssertFalse(result)
+    }
+}
+
+// MARK: - Constants
+
+private extension String {
+    static let error = "Value must be positive"
+}